2) Coagulation problems:
Blood coagulation refers to the ability of the blood to form a blood clot. The process is by no means simple and many mechanisms share in its formation. After the first platelet identifies the defective vessel wall, the coagulation cascade starts through the activation of many proteins called coagulation factors and the end product is the conversion of an inactive protein called fibrinogen to its active form “fibrin”. Fibrin then aggregates in the form of threads or fibers in between the aggregated platelets to form the blood clot. Defects in the coagulation pathway will result in easy bruising, but if isolated with no defects in platelets, it is highly unlikely that they will cause spontaneous bleeding. The most common defects in the coagulation pathway include:
- Hemophilia: hemophila is divided into 2 main types, A and B depending on the defective coagulation factor. Hemophilia A results from a defective factor VIII. This defect is inherited as a sex-related trait, which means that males are much more likely to be affected since they have only one copy of the X chromosome while females have 2 copies and if one of them doesn’t have a defective gene, the female won’t manifest any of the symptoms, but will carry it on to her sons. Hemophilia B is similar to hemophilia B but here, the defective factor is factor IX. In both cases, patients experience easy bruising and excessive bleeding following injury and can even become disabled due to repetitive bleeding into joints especially the knee joint.
- Von Willebrand factor deficiency: Von Willebrand factor is a protein that helps bind platelets to the vessel wall and initiate platelet adhesion and aggregation. It also helps start the coagulation pathway. Defective Von Willebrand factor will show manifestations of defective platelets and defective coagulation.